Nature's Awful Beauty

Built by Animals: The Natural History of Animal Architecture. Mike Hansell. viii + 257 pp. Oxford University Press, 2008. $29.95.

Consider the swallow, which industriously builds its nest by gathering straw and mud and then molding the mixture. Who can watch this process and not wonder, as Aristotle did, whether there is a purposeful intelligence at work? I could offer hundreds of other examples of such behavior. For millennia, structures built by animals have fascinated us in our incarnation as Homo teleologicus—seekers of purpose, design and meaning.

To the Nobel prize-winning ethologist Karl von Frisch, animal-built structures were a source of "awe in the face of the workings of nature." In his view, biologists "convinced that they, or future generations of scientists, will ultimately find the key of life in all its manifestations" were obvious dullards "to be pitied." His target when he wrote these words in 1972 was an overconfident reductionism that was promising to provide an ultimate answer to life—but at a Mephistophelian price: abandonment of the quest for purpose and beauty. To von Frisch, to make such a promise was hubris. The living world is rampant with beauty and purpose—a fact that he believed demands an explanation.

There is irony in von Frisch's challenge, though, for he was speaking as a member of another tribe—Homo darwiniensis, if you will—which claimed to have discovered its own key of life. And so the problem could be put with equal force to Darwinians: How do they account for the living world's seeming beauty and purposefulness?

The Darwinian "theory of everything" has always stood above its presumptive competitors because it came packaged with several "big problems," which could just as easily have been the theory's undoing as its vindication: altruism, sociality, organs of extreme perfection, and animal-built structures. With respect to the last one, the basic problem is that when we build, we act as purposeful, intentional and designing agents. Yet it is Darwinism's core assumption that such agency has no place in guiding evolution.

When animals build things, sometimes appearing to anticipate, match or exceed our own capabilities as architects, what are we to think? Do we conclude that other creatures can also act as intentional agents? In that case, the Darwinian vision of a world without such agency is undermined. Or do we conclude that our own intentionality is a quality apart, with no precedent in the living world from which we sprang? Drawing such a conclusion would be tantamount to succoring Darwin's bête noir, Platonic essentialism. This problem is not trivial: Indeed, it drove a wedge between Darwin and his "co-Darwinist," Alfred Russel Wallace. Yet Darwin himself, confronted with the magnificent structures built by bowerbirds, resorted to attributing them to the birds' pursuit of "pleasure"—a purposeful agency if ever there was one.

It is sobering to realize that only recently has the problem of animal-built structures been brought firmly into the Darwinian fold. Two people are primarily responsible for that having happened. One is Richard Dawkins, who argued in his 1982 book The Extended Phenotype—his most original work—that the structures animals build are just one case of a broader tendency of genes to modify environments to their own benefit. The other is Mike Hansell, whose landmark book Animal Architecture (1984, reissued in a new and much revised edition in 2005) put the meat, so to speak, on Dawkins's dazzling speculations. There, Hansell sought to do what Robert Trivers and the late William D. Hamilton did for the evolution of sociality and altruism: frame the subject in such a way that specific testable questions could be asked about it. Animal Architecture was aimed at a scholarly audience, though, and so was not as widely read as it might have been. Apparently Hansell and his publisher have now decided to rectify this with a book for a general audience. Built by Animals is the welcome result.

Hansell constructs his narrative around eight themes, ranging from a straightforward survey of which animals build things and which do not, to the relationship between intelligence and building, to the prevalence of tool-making and tool use, to the role that appreciation of craft and beauty might have played in the evolution of animal building. The book is a fascinating read, with personal anecdotes and reflections blending into thought-provoking explorations of the various themes. Hansell is an engaging writer with a remarkably clear and relaxed style, and he consistently does his readers the honor of respecting their intelligence. In short, this is a book to carry off to a quiet room with a crackling fireplace for a pleasant encounter with another mind.

In some instances, the narrative works brilliantly. In the chapter on trap building, for example, Hansell poses a thought-provoking question: Why is this activity rare among animals? It is a question that should intrigue anyone who has set a trap or watched a spider weave her snare. Hansell then springs a little trap himself. Such activity is, in fact, rare only among vertebrates, he says; doesn't this peculiar fact demand some explanation?

In other instances, Hansell's approach is not so effective. His chapter on why brains are not required for an animal to be a builder digresses into a long discussion of avian nest building that convincingly demonstrates (to me anyway) that brains are in fact quite necessary.

For me, the most appealing aspect of Built by Animals is its forthright honesty about the problem that animal-built structures have always posed to Homo darwiniensis: Do animals think about the world as we do, or do we only think they do? In an earlier time, asking such a question was verboten—Homo teleologicus crashing the reductionist party. The climate is different now, fortunately. As we come to think more deeply on big problems such as cognition and consciousness, and as the overconfident reductionism of the past seems to be bumping up against its limits, von Frisch's challenge rises anew: How do we account for nature's awful beauty?

Although Hansell convincingly argues that Darwinian natural selection is indeed the best account we currently have, he is honest enough to admit that it, too, faces serious challenges and that meeting them may involve indulging in what has long been regarded as a dangerous intellectual habit: anthropomorphism. We are more relaxed about such things now. Anthropomorphism has been demoted from unspeakable vice to mere sin, and this development has in turn led many to the discovery that sin has its uses. To quote Hansell, "I have to admit to always rather liking anthropomorphism not, I must emphasize, as an explanation but as a source of ideas."

This proclivity comes out most strongly in the last chapter, on the bowerbirds that so perplexed Darwin. Hansell finds himself drawing much the same conclusion Darwin did—that bowerbirds, like us, are not simply apparent connoisseurs of the things they build, they actually are connoisseurs, driven largely by a striving for beauty, which may be much like our own. Hansell asks whether the bowers are art, characterizing his question as "carelessly undisciplined." On the contrary: It is both intriguing and brave.